Understanding Digital Certificates on z/os Vanguard Las Vegas, NV Session AST3 June 26th 2012

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1 Understanding Digital Certificates on z/os Vanguard Las Vegas, NV Session AST3 June 26th 2012 Wai Choi, CISSP IBM Corporation RACF/PKI Development & Design Poughkeepsie, NY 1 Trademarks The following are trademarks of the International Business Machines Corporation in the United States and/or other countries. CICS* DB2* IBM* IBM (logo)* OS/390* RACF* Websphere* z/os* * Registered trademarks of IBM Corporation The following are trademarks or registered trademarks of other companies. Identrus is a trademark of Identrus, Inc VeriSign is a trademark of VeriSign, Inc Microsoft, Windows and Windows NT are registered trademarks of Microsoft Corporation. * All other products may be trademarks or registered trademarks of their respective companies. Notes: Performance is in Internal Throughput Rate (ITR) ratio based on measurements and projections using standard IBM benchmarks in a controlled environment. The actual throughput that any user will experience will vary depending upon considerations such as the amount of multiprogramming in the user's job stream, the I/O configuration, the storage configuration, and the workload processed. Therefore, no assurance can be given that an individual user will achieve throughput improvements equivalent to the performance ratios stated here. IBM hardware products are manufactured from new parts, or new and serviceable used parts. Regardless, our warranty terms apply. All customer examples cited or described in this presentation are presented as illustrations of the manner in which some customers have used IBM products and the results they may have achieved. Actual environmental costs and performance characteristics will vary depending on individual customer configurations and conditions. This publication was produced in the United States. IBM may not offer the products, services or features discussed in this document in other countries, and the information may be subject to change without notice. Consult your local IBM business contact for information on the product or services available in your area. All statements regarding IBM's future direction and intent are subject to change or withdrawal without notice, and represent goals and objectives only. Information about non-ibm products is obtained from the manufacturers of those products or their published announcements. IBM has not tested those products and cannot confirm the performance, compatibility, or any other claims related to non- IBM products. Questions on the capabilities of non-ibm products should be addressed to the suppliers of those products. Prices subject to change without notice. Contact your IBM representative or Business Partner for the most current pricing in your geography. 2 1

2 y Agenda Symmetric vs. Asymmetric Encryption What are digital certificates Certificate types and contents Overview of certificate utilities available on z/os Certificate formats Summary 3 Symmetric Encryption Same key used for both encryption and decryption Provide data confidentiality Fast, used for bulk encryption/decryption Securely sharing and exchanging the key between both parties is a major issue Common algorithms: DES, Triple DES, AES Secret Key y Encryption Algorithm Original Message This is a plain text Encrypted Message QWE@56!121!TQM y Decryption Algorithm y Same Secret Key 4 2

3 y y y Asymmetric Encryption 2 different keys - Public/private key pairs A public key and a related private key are numerically associated with each other. Provide data confidentiality, integrity and non repudiation Data encrypted/signed using one of the keys may only be decrypted/verified using the other key. Very expensive computationally Public key is freely distributed to others, private key is securely kept by the owner Common algorithms: RSA, DSA, ECC Private Key y Encryption Algorithm Original Message Encrypted Message This is a plain text QWE@56!121!TQM y Decryption Algorithm y Public Key (related to the private key) 5 Message Digest (Hash) A fixed-length value generated from variable-length data Unique: the same input data always generates the same digest value tiny change in data causes wide variation in digest value Theoretically impossible to find two different data values that result in the same digest value One-way: can t reverse a digest value back into the original data NOT based on a key Play a part in data integrity and origin authentication Common algorithms: SHA1, SHA256 Original Message I own you $10,000 y Hash Algorithm Digested Message 4E284BA3E B507A476B4A6538BAE7 Similar Message I own you $ y Hash Algorithm Totally different digested Message 5B0EBF53D5A30220BF68E88CCC04A4ACA3E

4 Encryption (for confidentiality) Encrypting a message: Sender: Msg Encrypt with Recipient s Public key Decrypting a message: Keys: Recipient: Plain text Encrypted text Decrypt with Recipient s Private key Msg 7 Signing (for integrity and non repudiation) Signing a message: Sender: Hash Msg Encrypt with Sender s Private key Msg + Signature Verifying a message: Recipient: Decrypt With Sender s Public key to recover the hash Keys: Plain text Message digest Msg Hash Do they match? If yes, the message is unaltered. Assuming the hashing algorithm is strong. MD5 was demonstrated broken on 12/30/08 Signature 8 4

5 What is a Digital Certificate (1 of 2) Generally digital certificates provide identity to a person or a server Person - like an ID card Server like a business license To establish an identity or credential to be used in electronic transactions It binds the public key to the identity to be used by applications that are based on public key protocols. (e.g. SSL/TLS) Issued by a trusted third party called Certificate Authority (CA) that can ensure validity 9 What is a Digital Certificate(2 of 2) Packaging of the information is commonly known as the x.509 digital certificate. X.509 defines the format and contents of a digital certificate. IETF RFC 5280 Digital certificates been in existence for over 20 years Have evolved over time to not only bind basic identity information to the public key but also how public key can be used, additional identity data, revocation etc. 10 5

6 What s s inside a Certificate? Certificate Info version serial number signature algorithm ID issuer s name validity period subject s name subject s public key extensions Certificate Signature Version 1, 2, 3 This is the hash/encrypt algorithm used in the signature, eg. sha256rsa Beware of MD5!!! The certificate binds a public key to a subject CA signs the above cert info by encrypting the hash with its private key The private key is NOT in the certificate. It is kept in a key store You can NOT change ANY of the certificate information! 11 Extensions of a x.509 digital Certificate(1 of 2) Adds additional definitions to a certificate and its identity information 15+ currently defined Top 6 extensions of interest Authority Key Identifier Subject Key Identifier Key Usage Subject Alternate Name BasicConstraints CRL Distribution Point 12 6

7 Extensions of a x.509 digital Certificate(2 of 2) Authority Key Identifier Unique identifier of the signer Subject Key Identifier Unique identifier of the subject Key Usage defines how the public key can used Digital Signature Key Encipherment Key Agreement Data Encipherment Certificate Signing CRL signing Subject Alternate Name additional identity information Domain name URI IP address Basic Constraints Certificate Authority Certificate or not CRL Distribution Locating of Revoked certificate information 13 Example of a x.509 digital Certificate 14 7

8 Relationship between Certificate and Certificate Store Certificate must be placed in a certificate store before it can be used by an application to perform identification or validation The application needs to retrieve the certificate and/or its corresponding private key from the store On z/os, many components like Communication Server, HTTP Server call System SSL APIs to access the store Certificate store = key ring = key file 15 Types of digital certificates who issues it Self signed Self-issued Issuer and subject names identical Signed by itself using associated private key Signed Certificate Signed/issued by a trusted Certificate Authority Certificate using its private key. By signing the certificate, the CA certifies the validity of the information. Can be a well-known commercial organization or local/internal organization. 16 8

9 Types of digital certificates what is the usage Secure Socket Layer (SSL) certificate Install on a server that needs to be authenticated, to ensure secure transactions between server and client Code Signing certificate Sign software to assure to the user that it comes from the publisher it claims Personal certificate Identify an individual, enable secure to prove that the really comes from the sender and /or encrypt the so that only the receiver can read it More (name it whatever you want) wireless certificate, smart card certificate Certificate Authority (CA) certificate Used to sign other certificates Root CA: the top Intermediate CA: signed by root CA or other intermediate CA 17 Types of digital certificates what is the usage Site certificate (in RACF) The usage assigned to a certificate when it is connected to a RACF key ring indicates its intended purpose There may be a few certificate validation applications which treat a certificate that is connected to a key ring with usage site as a valid certificate authority certificate to bypass the normal certificate verification tests during SSL handshake, for example, an expired certificate can be considered trusted Having a SITE certificate in RACF does not benefit you if the validation application does not make use of it 18 9

10 Certificate Stores on z/os gskkyman manages certificates stored in a key database file RACDCERT manages certificates stored in a RACF key ring. GSKKYMAN RACDCERT RACF Database CA Cert Key ring Server Cert CA cert CA cert Server cert 19 Certificate Store Protection gskkyman key database files Protected by the file system s permission bits and password Upon creation, permission bits are 700 giving the issuer of gskkyman read and write to the file only. Applications using these files need at least read to the file RACF Key Rings RACF key rings are protected by resource profiles. Users rings need read access to IRR.DIGTCERT.LISTRING or <ring owner>.<ring name>.lst to be able to read the contents of their key ring IRR.DIGTCERT.LISTRING Global control <ring owner>.<ring name>.lst Granular control 20 10

11 Certificate Utilities gskkyman is a Unix based utility shipped as part of the System SSL product in the z/os Cryptographic Services Element RACDCERT is a TSO command shipped as part of RACF Provide basic certificate functions Create/delete certificate store (HFS key database file / SAF key ring) Create certificate requests (to be signed by trusted Certificate Authority) Import/Export certificates (with and without private keys) Create self-signed certificates Do not have all the functions of a real Certificate Authority 21 Certificate Authority on z/os PKI Services provides full certificate life cycle management Request, create, renew, revoke certificate Provide certificate status through Certificate Revocation List(CRL) and Online Certificate Status Protocol (OCSP) Generation and administration of certificates via customizable web pages Support Simple Certificate Enrollment Protocol (SCEP) for routers to request certificates automatically Automatic notification or renewal of expiring certificates 22 11

12 Defining a Certificate How will the certificate be used? What certificate store is to be used? Who will be the certificate authority? What is the size of the public/private keys? What subject name to use? Need additional identity information and extensions? 23 Defining a Certificate Request to be signed by a CA A certificate signing request (also CSR) is a message sent from the certificate requestor to a certificate authority to obtain a signed digital certificate Contains identifying information and public key for the requestor Corresponding private key is not included in the CSR, but is used to digitally sign the request to ensure the request is actually coming from the requestor CSR may be accompanied by other credentials or proofs of identity required by the certificate authority, and the certificate authority may contact the requestor for further information. If the request is successful, the certificate authority will send back an identity certificate that has been digitally signed with the private key of the certificate authority

13 If you use gskkyman 25 Create a key database Database Menu 1 - Create new key database 2 - Open key database 3 - Change database password 4 - Change database record length 5 - Delete database 6 - Create key parameter file 7 Display certificate file (Binary or Base64 ASN.1 DER) 0 - Exit Program Name of key database Enter your option number: 1 Enter key database name (press ENTER to return to menu: /tmp/my.kdb Enter database password (press ENTER to return to menu: password Re-enter database password: password Enter password expiration in days (press ENTER for no expiration): <enter> Enter database record length (press ENTER to use 2500): <enter> This will add a number of well-known trusted CA certificates to the key database

14 Importing a signing Certificate Authority Certificate Key Management Menu Database: /tmp/my.kdb 1 - Manage keys and certificates 2 - Manage certificates 3 - Manage certificate requests 4 - Create new certificate request 5 - Receive requested certificate or a renewal certificate 6 - Create a self-signed certificate 7 - Import a certificate 8 - Import a certificate and a private key 9 - Show the default key 10 - Store database password 11 - Show database record length 0 - Exit program Enter option number (press ENTER to return to previous menu): 7 27 Importing a signing Certificate Authority Certificate Continued Enter import file name (press ENTER to return to menu): cacert.b64 Enter label (press ENTER to return to menu): CA Certificate Certificate imported. File contains the CA certificate 28 14

15 Creating a new certificate request Key Management Menu Database: /tmp/my.kdb 1 - Manage keys and certificates 2 - Manage certificates 3 - Manage certificate requests 4 - Create new certificate request 5 - Receive requested certificate or a renewal certificate 6 - Create a self-signed certificate 7 - Import a certificate 8 - Import a certificate and a private key 9 - Show the default key 10 - Store database password 11 - Show database record length 0 - Exit program Enter option number (press ENTER to return to previous menu): 4 29 Fill in the information about the requestor (1of 2) Certificate Key Algorithm 1 - Certificate with an RSA key 2 - Certificate with a DSA key 3 - Certificate with an ECC key Select certificate key algorithm (press ENTER to return to menu): 1 RSA Key Size bit key bit key bit key Select RSA key size (press ENTER to return to menu): 2 Signature Digest Type 1 - SHA SHA SHA SHA SHA-512 Select digest type (press ENTER to return to menu):

16 Fill in the information about the requestor(2 of 2) Enter request file name (press ENTER to return to menu): certreq.arm Enter label (press ENTER to return to menu): Server Certificate Enter subject name for certificate Common name (required): Server Certificate Organizational unit (optional): Production Organization (required): IBM City/Locality (optional): Endicott State/Province (optional): New York Country/Region (2 characters - required): US Enter 1 to specify subject alternate names or 0 to continue: 1 File to contain certificate request 31 Receiving a signed certificate request Key Management Menu Database: /tmp/my.kdb 1 - Manage keys and certificates 2 - Manage certificates 3 - Manage certificate requests 4 - Create new certificate request 5 - Receive requested certificate or a renewal certificate 6 - Create a self-signed certificate 7 - Import a certificate 8 - Import a certificate and a private key 9 - Show the default key 10 - Store database password 11 - Show database record length 0 - Exit program Enter option number (press ENTER to return to previous menu): 5 Enter certificate file name (press ENTER to return to menu): svrcert.arm File contains cert returned from CA 32 16

17 Marking a certificate as the default Key and Certificate Menu Label: Server Certificate 1 - Show certificate information 2 - Show key information 3 - Set key as default 4 - Set certificate trust status 5 - Copy certificate and key to another database 6 - Export certificate to a file 7 - Export certificate and key to a file 8 - Delete certificate and key 9 - Change label 10 - Create a signed certificate and key 11 - Create a certificate renewal request 0 - Exit program Enter option number (press ENTER to return to previous menu): 3 33 If you use RACDCERT (ISPF Panel or Command) 34 17

18 RACDCERT Panel on Key Ring 35 RACDCERT Panel on Certificate 36 18

19 Create a key ring Name of key ring RACDCERT ID(FTPserver) ADDRING(MyRACFKeyRing) Adding Certificate Authority(CA) Certificate to a key ring Dataset contains the CA certificate RACDCERT CERTAUTH ADD( user1.cacert ) TRUST WITHLABEL( CA Certificate ) RACDCERT ID(FTPServer) CONNECT (CERTAUTH LABEL( CA Certificate ) RING(MyRACFKeyRing) USAGE(CERTAUTH)) 37 Creating a new certificate request RACDCERT ID(FTPServer) GENCERT SUBJECTSDN(CN( Server Certificate )OU( Production )O( IBM )L( Endicott )SP( New York )C( US )) SIZE(1024) WITHLABEL( Server Certificate ) ALTNAME(DOMAIN( mycompany.com')) RACDCERT ID(FTPServer) GENREQ(LABEL( Server Certificate )) DSN( user1.certreq ) Dataset to contain certificate request 38 19

20 Adding Certificate signed by CA to a key ring RACDCERT ID(FTPServer) ADD( user1.svrcert ) WITHLABEL( Server Certificate ) RACDCERT ID(FTPServer) CONNECT(ID(SUIMGTF) LABEL( Server Certificate ) RING(MyRACFKeyRing) USAGE(PERSONAL) DEFAULT) Dataset contains cert returned from CA 39 Listing a RACF Key Ring RACDCERT ID(FTPServer) LISTING(MyRACFKeyRing) Ring: >MyRACFKeyRing< Certificate Label Name Cert Owner USAGE DEFAULT CA Certificate CERTAUTH CERTAUTH NO Server Certificate ID(FTPServer) PERSONAL YES Note: RACF key rings allow for a certificate s private key to be stored into ICSF s (Integrated Cryptographic Service Facility) PKDS (Public Key Dataset) for added security

21 Certificate Formats X.509 certificates can exist in many different forms Single certificate PKCS #7 certificate package Contains 1 or more certificates PKCS #12 certificate package A password encrypted package containing 1 or more certificates and the private key associated with the endentity certificate. Only package type that contains a private key Can be in binary or Base64 encoded format 41 Base64 encoding Converting binary data to displayable text for easy cut and paste BEGIN CERTIFICATE----- MIICPTCCAaagAwIBAgIIR49S4QANLvEwDQYJKoZIhvcNAQEFBQAwNzELMAkGA1UE BhMCVVMxDTALBgNVBAoTBFRlc3QxGTAXBgNVBAMMEFRlc3Rfc2VsZl9zaWduZWQw HhcNMDgwMTE3MTMwNjQxWhcNMDkwMTE2MTMwNjQxWjA3MQswCQYDVQQGEwJVUzEN MAsGA1UEChMEVGVzdDEZMBcGA1UEAwwQVGVzdF9zZWxmX3NpZ25lZDCBnzANBgkq hkig9w0baqefaaobjqawgykcgyea9tkov5glaceozmfmevd891fcjbvor+dpzhwk R2B/QcQYBGLfqS4YM/wGSh6YrmVygO0VxocriySbcxRuBayw3pE4/3JI2myINmLp bfidpcnqk/qvfk+1n+nrenbk9yls7nmxdiuqqffsx/o/dpoxwxzwxf+jbwdwirqr NyLiTGMCAwEAAaNSMFAwHQYDVR0OBBYEFAwDFLjOUCRa62BVs3jVyHewuOWEMB8G A1UdIwQYMBaAFAwDFLjOUCRa62BVs3jVyHewuOWEMA4GA1UdDwEB/wQEAwIE8DAN BgkqhkiG9w0BAQUFAAOBgQAC5sW1f3EdE0k9zc8wKNt1sczWkQBrVy4Rdrl7ERqN D2OfkBJQuXiNwN18pF6WPWfYG80MNwhP4oJSVePnzElh4Wzi2wl/zI8rINSW7px3 w16lz+8jei84q/n0q0toptateb6fizwjkltctt3of+ijunve5qorsxrjbbtmd/eg jw== -----END CERTIFICATE

22 Exporting Certificates through gskkyman Key and Certificate Menu Label: Server Certificate 1 - Show certificate information 2 - Show key information 3 - Set key as default 4 - Set certificate trust status 5 - Copy certificate and key to another database 6 - Export certificate to a file 7 - Export certificate and key to a file 8 - Delete certificate and key 9 - Change label 10 - Create a signed certificate and key 11 - Create a certificate renewal request 0 - Exit program Enter option number (press ENTER to return to previous menu): 43 Exporting Certificates through gskkyman Option 6 Public Certificate Information Export File Format 1 - Binary ASN.1 DER 2 - Base64 ASN.1 DER 3 - Binary PKCS #7 4 - Base64 PKCS #7 Option 7 Public Certificate Information and Private Key Export File Format 1 - Binary PKCS #12 Version 1 (Few very old applications still use V1) 2 - Base64 PKCS #12 Version Binary PKCS #12 Version Base64 PKCS #12 Version

23 Exporting Certificates through RACDCERT(1 of 2) RACDCERT ID(userid) EXPORT (LABEL('label-name')) DSN(output-data-set-name) FORMAT(CERTDER CERTB64 PKCS7DER PKCS7B64 PKCS12DER PKCS12B64 ) PASSWORD('pkcs12-password') Example - Export Server Certificate with its private key RACDCERT ID(FTPServer) EXPORT LABEL( Server Certificate ) DSN( USER1.SERVER.CERT ) FORMAT(PKCS12DER) PASSWORD( passwd ) 45 Exporting Certificates through RACDCERT(2 of 2) Precaution needed for CERTAUTH certificate when you plan to preserve the certificate and the private key by exporting them in a pkcs12 package If the original CERTAUTH certificate got deleted and you re-add this package, the field that used for recording serial numbers that it has issued is not reserved For example, if this CA certificate has issued 100 certificates, the next certificate to be issued should have serial number 101; but after re-adding it, the certificate to be issued will have serial number 1, which is already used all the certificates issued by the same CA should have a unique serial number! Before deleting CERTAUTH certificate, find out the last certificate s serial number it issued After re-adding, use r_datalib to bump up the serial number field to the appropriate number 46 23

24 Summary Digital certificates provide electronic identity and public key information to be utilized through public key protocols (ie. SSL/TLS) Utilizing trusted CAs is key to ensure validity of the digital certificate Protect the private key!!! Larger the public/private key pair size, greater security, but more computation intense 47 Summary When transferring certificates, use a format acceptable to the receiving side. When transferring certificates, be sensitive to binary and text modes to ensure proper transfer 48 24

25 References IBM Education Assistant web site: RACF web site: PKI Services web site: IBM Redbooks z/os V1 R8 RACF Implementation (SG ) Security Server Manuals: RACF Command Language Reference (SC ) RACF Security Administrator's Guide (SC ) Cryptographic Server Manual Cryptographic Services System Secure Sockets Layer Programming (SC ) RFCs RFC Internet X.509 Public Key Infrastructure Certificate and CRL Profile RFC Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) Profile 49 Questions? Questions or Time for Coffee? See you later in ATS4 (PKI Services) 50 25